I have found some sort of mineshaft Duplication bug in the world gen. I was in my survival world when I found it, and I plotted points in which the mineshafts generated (the dirt rooms). I loaded up another world (ibxtoycats world on seed sunday) and I found also the same exact formation. Also it does not 100% duplicate it I don't think, but only the area around the dirt room. I believe you can reproduce this bug on any seed, but I'm not certain. The mineshafts create 2 diagonally from each other 16 blocks apart, then in the other direction to make a rectangle, does 2 more mineshafts 32 blocks from the former. Back the first direction, goes 64 blocks and connects to another square, up to four times (in my experience, may be different in other seeds). The seeds for these in the photos below are RegalSpork and 1995059250. This is quite a big bug, and it's very strange, I hope you guys can figure it all out. God Bless! (edit) I don’t know why all the photos are in random order, sorry for that, also the wood and diamond pillars are where mineshaft are located